This invention relates to a water pump for controlling the heating and cooling of an internal combustion gasoline or diesel engine by controlling the flow of temperature control fluid through the engine.
Page 169 of the Goodheart-Willcox automotive encyclopedia, The Goodheart-Willcox Company, Inc., South Holland, Ill., 1995 describes that as fuel is burned in an internal combustion engine, about one-third of the heat energy in the fuel is converted to power. Another third goes out the exhaust pipe unused, and the remaining third must be handled by a cooling system. This third is often underestimated and even less understood.
Most internal combustion engines employ a pressurized cooling system to dissipate the heat energy generated by the combustion process. The cooling system circulates water or liquid coolant through a water jacket which surrounds certain parts of the engine (e.g., block, cylinder, cylinder head, pistons). The heat energy is transferred from the engine parts to the coolant in the water jacket. In hot ambient air temperature environments, or when the engine is working hard, the transferred heat energy will be so great that it will cause the liquid coolant to boil (i.e., vaporize) and destroy the cooling system. To prevent this from happening, the hot coolant is circulated through a radiator well before it reaches its boiling point. The radiator dissipates enough of the heat energy to the surrounding air to maintain the coolant in the liquid state.
In cold ambient air temperature environments, especially below zero degrees Fahrenheit, or when a cold engine is started, the coolant rarely becomes hot enough to boil. Thus, the coolant does not need to flow through the radiator. Nor is it desirable to dissipate the heat energy in the coolant in such circumstances since internal combustion engines operate most efficiently and pollute the least when they are running relatively hot. A cold running engine will have significantly greater sliding friction between the pistons and respective cylinder walls than a hot running engine because oil viscosity decreases with temperature. A cold running engine will also have less complete combustion in the engine combustion chamber and will build up sludge more rapidly than a hot running engine. In an attempt to increase the combustion when the engine is cold, a richer fuel is provided. All of these factors lower fuel economy and increase levels of hydrocarbon exhaust emissions.
To avoid running the coolant through the radiator, conventional coolant systems employ a thermostat. The thermostat operates as a one-way valve, blocking or allowing flow to the radiator. Most prior art coolant systems employ wax pellet type or bimetallic coil type thermostats. These thermostats are self-contained devices which open and close according to precalibrated temperature values.
Coolant systems must perform a plurality of functions, in addition to cooling the engine parts. In cold weather, the cooling system must deliver hot coolant to heat exchangers associated with the heating and defrosting system so that the heater and defroster can deliver warm air to the passenger compartment and windows. The coolant system must also deliver hot coolant to the intake manifold to heat incoming air destined for combustion, especially in cold ambient air temperature environments, or when a cold engine is started. Ideally, the coolant system should also reduce its volume and speed of flow when the engine parts are cold so as to allow the engine to reach an optimum hot operating temperature. Since one or both of the intake manifold and heater need hot coolant in cold ambient air temperatures and/or during engine start-up, and since these components are normally situated along the same flow circuit as the engine block, it is not practical to completely shut off the coolant flow through the engine block.
Numerous proposals have been set forth in the prior art to more carefully tailor the coolant system to the needs of the vehicle and to improve upon the relatively inflexible prior art thermostats. The inventor of the present invention has patented several such improvements. In particular, U.S. Pat. Nos. 5,503,118, 5,458,096, and 5,724,931 disclose improvements to conventional cooling systems. These prior art references are incorporated herein in their entirety by reference.
A water pump is used in conventional engines to circulate coolant through the engine. Prior art water pumps are limited in functionality in that they simply act as a mechanism for transmitting the flow of fluid. These prior art water pumps lack the ability to selectively distribute temperature control fluid to various parts of an internal combustion engine in a controlled manner so as to ensure the engine is operating at an optimal temperature level. An example of one type of conventional prior art water pump is described in U.S. Pat. No. 6,056,518.
Accordingly, a need therefore exists for a water pump that is capable of optimally controlling the flow of a fluid in a cooling system and is compatible with the current engine arrangement.
An improved water pump is disclosed for an internal combustion engine. The engine includes an engine block, an air-intake manifold, at least one cylinder head, and an exhaust manifold. The water pump operates in conjunction with a valve for controlling the flow of temperature control fluid through the engine in response to commanded signals in order to maintain the engine (and/or engine oil) at or near a desired temperature for maximum efficiency.
The water pump includes a housing with an inlet, a bypass inlet and an outlet. The water pump disperses temperature control fluid to the engine block through the outlet and receives temperature control fluid through the inlet and bypass inlet. Within the housing is an electric motor assembly for causing the water to flow from the inlet to the outlet. An electronic engine temperature control valve is mounted to the inlet and has a first and second position. When the control valve is in the first position, flow is permitted to travel from the inlet to the electric motor assembly. When the control valve is in the second position, flow is inhibited from traveling from the inlet to the electric motor assembly.
The control valve is adapted to receive signals from an electronic control system for controlling the actuation of the valve between the first and second positions. The bypass inlet is adapted to receive flow of temperature control fluid from a bypass passage and channel the flow to the electric motor assembly. The control valve is adapted to substantially close the bypass inlet when in the first position so as to inhibit flow from the bypass passage to the electric motor assembly.